Introduction to
Biology
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Biology – The Study of Life
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Life arose more
than 3.5 billion
years ago
First organisms
(living things) were
single celled
Only life on Earth
for millions of
years
Organisms changed
over time (evolved)
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New organisms
arose from older
kinds
Today there are
millions of species
They inhabit
almost every
region of Earth
today
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Themes of Biology
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Cell structure and
function
Stability and homeostasis
Reproduction and
inheritance
Evolution
Interdependence of
organisms
Matter, energy, and
organization
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Cell Structure and Function
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Cell basic unit of life
All organisms are
made of and develop
from cells
Some composed of
only a single cell
(unicellular) which is
usually identical to
parent
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Cells
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Most organisms are
composed of many
cells (multicellular)
 Cells are
different (undergo
differentiation)
Cells are small
Cells are highly
organized
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Cells contain specialized
structures (organelles)
that carry out the cell’s
life processes
Many different kinds of
cells exist
All cells surrounded by a
plasma membrane
Contain a set of
instructions called DNA
(genetic information)
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Stability and Homeostasis
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Organisms must Maintain very stable
internal conditions HOMEOSTASIS
Temperature, water content,
chemical content, etc. must be
maintained
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Reproduction and Inheritance
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All organisms produce new organisms
like themselves REPRODUCE
Organisms transmit hereditary
information to their offspring
INHERITANCE
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DNA
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Genetic Information in all cells
Deoxyribonucleic Acid
DNA contains instructions for
traits GENES
Make the structures and
complex chemicals necessary
for life PROTEINS
DNA in every body cell
(SOMATIC CELLS) is exactly
alike
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Sexual Reproduction
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Hereditary information
from two different
organisms of the same
species are combined
Egg and sperm 
zygote (fertilized egg)
Zygote contains
hereditary information
from both parents
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Asexual Reproduction
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Hereditary information
from one, usually
unicellular, organism
that divides
Resulting cells contain
identical hereditary
information
Genetic information
from single parent
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Evolution
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Populations of organisms
change (evolve) over
generations (time)
Explains how many
different kinds of
organisms came into
existence SPECIES
Explains how modern
organisms are related to
past organisms
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Explains why
organisms look and
behave the way
they do
Provides a basis
for exploring the
relationships
among different
groups of
organisms
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Natural Selection
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Natural selection is the
driving force in evolution
Organisms that have certain
favorable traits are better
able to successfully
reproduce than organisms
that lack these traits
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Natural Selection
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Survival of organisms with
favorable traits cause a
gradual change in populations
over many generations
Also Called “Survival of the
Fittest”
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Interdependence of Organisms
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Interaction of
organisms with one
another and with
their environment
ECOLOGY
Insects depend and
flowers DEPEND on
each other for food &
pollination
COEVOLUTION
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All organisms need substances such
as nutrients, water, and gases from
the environment
The stability of the environment
depends on the healthy functioning of
organisms in that environment
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Matter, Energy and
Organization
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Living things are highly organized
Require a constant supply of energy
to maintain their orderly state
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Energy
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ALL energy comes from the SUN
(directly or indirectly)
Photosynthesis is the process by
which some organisms capture the
energy from the sun (solar) and
transform it into energy (chemical)
that can be used by living things
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Autotrophs
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Organisms that make their
own food are called
autotrophs
Phototrophs – use solar
energy (photosynthesis) to
get energy
Convert H2O and CO2 into
sugar and O2
Chemotrophs – use different
chemical processes to get
energy
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Heterotrophs
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Organisms that must take in
food to meet their energy
needs are called heterotrophs
Consume autotrophs
(herbivores), other
heterotrophs (carnivores) or
both (omnivores) for their
energy needs
Complex chemicals are broken
down and reassembled into
chemicals and structures
needed by organisms
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The World of Biology
Chapter 1.2
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Characteristics of Life
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Cells
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All living things are
composed of cells
In multicellular
organisms, many are
specialized to perform
specific functions
Cells are always very
small
The size of multicelled organisms
depends on the number
of cells NOT their size
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Organization
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Organized at both the
molecular and cellular
levels
Take in substances
from the environment
and organize them in
complex ways
Specific cell
structures (organelles)
carry out particular
functions
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In multicellular
organisms, cells
and groups of
cells (tissues) are
organized by
their function
 Cells 
tissues
 Tissues 
organs
 Organs 
systems
 Systems 
 ORGANISMCopyright Cmassengale
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Energy Use
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Use energy in a process called metabolism
 Sum of all chemical processes
Require energy to maintain their molecular
and cellular organization, grow and
reproduce
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Homeostasis
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Maintain stable internal conditions
Temperature, pH, etc.
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Growth
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Grow occurs as the result of cell
division and cell enlargement
Cell division is the formation of two
cells from a preexisting cell
New cells enlarge as they mature
When a cell grows to a size where
its surface area isn’t big enough
for its volume, the cell divides
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Development
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The process by which an adult organism
arise is called development
 Repeated cell divisions and cell
differentiation
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Reproduction
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All species have the ability to reproduce
 Not essential to survival of individual
but is essential for continuation of a
species
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Responsiveness
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Respond to stimuli in the
external environment
Detect and respond to
changes in light, heat,
sound and chemical and
mechanical contact
Coordinates it’s
responses
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Evolve
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Ability to adapt to their environment
through the process of evolution
Favorable characteristics are selected for
and passed on to offspring
Called adaptations
Driven by
natural selection
or “survival of the
fittest”
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Scientific Method
Chapter 1.3
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Observation – STEP 1
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Employing your five senses to
perceive objects or events
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Asking a Question
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Based on observations; one or more
questions are generated
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Forming a Hypothesis – STEP 2
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A statement is testable if evidence can be
collected that either does or doesn’t
support it
It can never be proven beyond doubt
Often must be refined and revised or
discarded
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The Hypothesis --
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Is a statement made in advance
that states the results that will
be obtained from testing the
hypothesis
Often written in the form of an
“if-then” statement
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Experimenting – STEP 3
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Testing a hypothesis or prediction by
gathering data under controlled conditions
– conducting a controlled experiment
 Based on a comparison of a control
group with an experimental group
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Both groups are identical except for
one factor (independent variable)
Observations and measurements are
taken for a particular factor
(dependent variable) in both groups
 Driven by or results from independent
variable
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Measuring
 Involves quantitative data that can
be measured in numbers &/or
qualitative data information that
isn’t numbers
Sampling
 Technique of using a sample – a
small part – to represent the
entire population
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Organizing Data – STEP 4
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Involves placing observations and
measurement (data) in order
 Graphs, charts, tables, or maps
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Analyzing Data – STEP 4 cont)
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Collected and organized data must be
analyzed
 Process of determining whether data
are reliable or whether they support or
do not support a hypothesis or
prediction
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Conclusion – STEP 5
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Conclusions are made on the
basis of facts, not observations
 Often drawn from data
gathered from a study or
experiment
 Should support the
hypothesis
 Should be re-testable
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Communication – STEP 6
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Scientists must share the results of
their studies with other scientists
(peers)
Publish findings in journals
Present their findings at scientific
meetings
Scientists must be unbiased
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Should not tamper with their data
Only publish & report tested & proven
ideas
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Communication
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Sharing of information is essential to
scientific process
Subject to examination and verification
by other scientists
Allows scientists to build on the work of
others
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Theories
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A theory may be formed
after many related
hypotheses have been
tested and supported with
experimental evidence
A broad and comprehensive
statement of what is
thought to be true
Supported by considerable
evidence
Ties together related
hypotheses
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Laws
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A Statement of fact that concisely
explains an action or group of
actions
e.g. Law of Gravity
Accepted to be true
Universal
May be expressed as a math
equation
e.g. E=mc2
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MICROSCOPES
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Microscopy and Measurement
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Microscopes – produce an enlarged image
of an object
 Used to study organisms, cells, and cell
parts
 Increase in apparent size is called
magnification
 The ability to show details clearly is
called resolution
 Microscopes vary in both magnification
and resolution
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Compound
Light
Specimen mounted
on Microscopes
a glass slide
Must be thinly sliced
or very small
Pair of lenses
 Ocular lens (eye
piece)
 Objective lens
(nose piece)
Can be used to
study LIVE
specimens
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Magnification determined by multiplying
power of both lenses
Eyepiece 10X times Objective power (20X,
40X…)
Highest Maximum magnification is around
1000X
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Electron Microscope
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Transmission EM (TEM)
 Uses a beam of electrons
to produce an enlarged
image of very thinly
sliced specimen on screen
or photographic plate
 Image focused by
magnetic lenses
 200,000X magnification
 Cannot be used to view
living specimens
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Scanning EM (SEM)
 3D image
 Specimens not sliced
for viewing
 Surface sprayed with
fine metal coating
 Also uses electron
beam and fluorescent
screen or photographic
plates
 100,000X magnification
 Cannot be used to view
living specimens
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MEASUREMENTS
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Measurements
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We will be using SI units or metric
system when possible --- the WHOLE
world uses it except us (USA)
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